(HCF) Any of several undocumented and semi-mythical machine instructions with destructive side-effects, supposedly included for test purposes on several well-known architectures going as far back as the IBM 360. The Motorola6800microprocessor was the first for which an HCF opcode became widely known. This instruction caused the processor to toggle a subset of the bus lines as rapidly as it could in some configurations this could actually cause lines to burn up. [Confirm?] (1995-12-14)
